Well unloading process and apparatus therefor



WELL UNLOADING PROCESS AND APPARATUS THEREFOR v -Filed April 25, 1965 C. R. LYLES Feb. 2l,1967

5 Sheets-Sheet 1 C R. LYL ES INVENTOR ATTORNEY WELL UNLOADING PROCESS AND APPARATUS THEREFOR Filed April 23, 1965 C. R. LYLES Feb. 21, 1967 s Shets-Sheet 2 C. R. LYLE S INVENTOR.

jf ammk ATTORNEY Feb. 21, 1967 c. R. LYLES 3,304,374

WELL UNLOADING PROCESS AND APPARATUS THEREFOR Filed April 23, 1965 5 Sheets-Sheet 5 F/G/Z i CR. LYLES INVENTOR.

ATTORNEY c. R. LYLES 3,304,874

WELL UNLOADING PROCESS AND APPARATUS THEREFOR Feb.21, 1967 5 Sheets-Sheet 4 Filed April 25, 1965 C. R. LYL ES INVENTOR.

ATTORNEY C. R. LYLES Feb. 21, 1967 WELL UNLOADING PROCESS AND APPARATUS THEREFOR Filed April '25, 1965 FIG/8 C. R. LYL ES INVENTOR.

ATTORN EY United States PatentOfiYice 3,304,874 Patented Feb. 21, 1967 3,304,874 WELL UNLOADING PROCESS AND APPARATUS THEREFOR Cecil Ray Lyles, Box 836, Farmington, N. Mex. 78103 Filed Apr. 23, 1965, Ser. No. 450,492 12 Claims. (Cl. 10352)' This application is an improvement over my co-pending patent application Serial No. 303,001 filed August 19, 1963, now Patent No. 3,195,523 granted July 20, 1965.

This invention relates to a process of unloading a low oil-gas ratio well, to a gaslift plunger adapted to serve to raise oil from the bottom of such wells for use in such process, to upper and lower tubing stops for use with such a plunger in such process, and to the combination of such stops and plunger. 7

One object of this invention is to provide an improved method of unloading low production oil and gas wells and apparatus therefor.

Another object of this invention is to proved gaslift plunger.

Yet another object of this invention is to provide improved tubing stops. Still a further object of this invention is to provide a process for unloading oil and gas wells where there is usually a paraifin deposition problem and apparatus therefor.

Other objects of this invention will become apparent to those skilled in the art on a study of the below description of which description the hereto attached drawings form a part, and in which drawings the same number refers to the same part throughout all the drawings and wherein:

FIGURE 1 is a side view of one apparatus, 51, of this invention in a portion of a string of oil well tubing with the sealing subassemblies of apparatus 51 shown in open position; the apparatus is shown as seen in the direction of the arrow 1A in FIGURE 3 with the tubing portion shown in diametrical section normal to arrow 1A;

FIGURE 2 is a side view of the apparatus 51 of FIG- URE 1 shown as seen along the direction of the arrow 2A of FIGURE 4, said apparatus being shown with its sealing subassemblies in sealing position in a portion of a string of oil well tubing, such tubing portion being shown in diametral section normal to the direction of arrow 2A;

FIGURE 3 is an end view of the apparatus of FIG- URE 1 as seen along the direction of arrow 3A of FIG- URE 1;

FIGURE 4 is an end view of the apparatus of FIG- URE 1 taken along the direction of the arrow 4A of FIGURE 2;

FIGURE 5 is a composite longitudinal section view of the apparatus 51 in the position of its parts shown in FIGURES 1 and the zones 5A and 5B of FIG- URE 5 are shown as seen in section 5C5D of FIGURE 7; zone SE of FIGURE 5 is shown in section SF-SG of FIGURES 7 and 8;

FIGURE 6 is a longitudinal cross-section generally along planes 5F5G of FIGURE 7 and 6A of FIGURE 8 of the apparatus 51 in the position of its parts shown in FIGURES 2 and 11;

FIGURE 7 is a transverse cross-sectional view of the apparatus 51 in the position of the parts thereof shown in FIGURES 1 and 5, the cross sectional view being taken along the plane 7A-7B-7C of FIGURE 5;

FIGURE 8 is a top view of apparatus 51 showing the seal segment 131 and neighboring structures as seen along the direction of arrow 8A of FIGURE 5; arrow 8A is perpendicular to the outer surface of the fiat plate'SS;

provide an im- FIGURE 9 is a bottom view of the seal segment shown in FIGURE 8;

FIGURE 10 is a diagrammatic representation of the apparatus of FIGURE 1 during its operation in a well tubing, theapparatus being shown in two of its transitory positions while downwardly moving in said tubing with the sealing subassemblies thereof in their open position;

FIGURE 11 is a diagrammatic representation of the apparatus of FIGURE 1 during its operation in a well tubing, the apparatus being shown in two of its transitory positions while upwardly moving in said tubing with its sealing subassemblies in their sealing position as in FIG- URE 2 according to a process of this invention;

' FIGURE 12 is a diagrammatic representation of the apparatus of FIGURE 1 during its operation in a well tubing according to a process of this invention, the apparatus being shown in an upper operative position with its sealing subassemblies in their sealed position as in FIGURE 2;

FIGURE 13 is a composite side and longitudinal sectional view of the lower tubing stop 72, viewed along the vertical flat surfaces indicated as 13A, 13B, and 13C of FIGURE 16, in the movable condition of that tubing stop;

FIGURE 14 is a composite side and longitudinal view of the tubing stop 72, shown as in FIGURE 13, in the fixed condition of that tubing stop;

FIGURE 15 is a view, taken as in FIGURE 13, of the upper portion of the lower tubing stop 72, in the compressed position of that stop in a stage of operation between the stages shown in FIGURES 10-and 11;

FIGURE 16 is a top view taken along arrow 16A of FIGURE 14;

FIGURE 17 is a view, partly in section, of an upper tubing stop according to this invention in its expanded position, the view is taken along planes 17A and 17B of FIGURE 19;

FIGURE 18 is a view as for FIGURE 17 of the upper tubing stop shown as in FIGURE 17 in its compressed condition; and

FIGURE 19 is a transverse section view along planes 19A, 19B of FIGURE 17.

The plunger apparatus 51 is intended to operate in a well generally shown as 60. The well 60 comprises a string of tubing 61, and a producing formation as 64. The string of tubing has a discharge 65 above the surface, 66 of the formation. A casing 69 surrounds the string 61 and provides an annular space 70 therebetween.

The casing 69 is open near its bottom through perforations, as 67, to the producing formation 64. According to a preferred embodiment of process and apparatus of this invention, conventional packers as 76 and 77, 78, 79 are inserted in the annular zone 70 for purposes as below described. The string 61 is composed of a series of conventional lengths of conventional tubing as 41, 42, 43, 44, 45, 46, 47 of like internal diameter conventionally joined in series as by conventional exterior collars, as 41A between lengths 41 and 42, 43A between lengths 43 and 44, 44A between lengths 44 and 45.

The well tubing is provided with an upper stop 71 near its upper end and a lower stop 72 near its lower end. The uppermost length of tubing 56 is operatively and directly connected to the discharge outlet pipe 65. Outlet 65 is operatively connected to outlet control subassembly 190.

The upper stop 71 is located in the string 61 so that the sealing subassemblies as 57 and 58 of apparatus 51 will not rise above the bottom of the tubing discharge orifice, 68, to the discharge outlet pipe 65. A lower stop 72 is located in the string 61 as below described.

The apparatus 51 is a reciprocating plunger or piston and is shown in FIGURE 1 in its vertical position, which is the position in which it operates within the string 61. It comprises a frame subassembly 53, a piston subassembly 55, and a series of like sealing subassemblies 57 and 58.

The major components of the frame 53 are a fiat rectangular front plate 81, a fiat rectangular rear plate 83, a flat rectangular left plate 85, and a flat rectangulr right plate 87, an upper cap 90 and a lower cap 92. The plates and cap 92 are firmly and permanently attached together. Cap 90 is removable for purpose of assembly but also firmly attached to the plates 81, 83, 85, and 87. These plates and caps have orifices, grooves, and channels therein as below described and form a hollow rigid structure, square in transverse section, with diagonally extending corner elements. The corner elements extend substantially to the inner wall of the tubing 41, allowing for drift diameter thereof, with a loose fit which fit provides for maintaining the entire apparatus 51 with its longitudinal axis parallel to the axis of the adjacent tubing as 41. More particularly, front left corner plate elements 82A, 82B, 82C, and rear left corner plates 84A, 84B, 84C are attached to the left plate 85 at its front and rear as shown in FIGURES 1 and 7. Additionally, front right corner plates 86A, 86B, 86C and rear right corner plates 88A, 88B, 88C are attached to the right plate 87 as shown in FIGURE 7. These corner plates are also attached to the front and rear plates as shown in the figures. The plate 82A, 82B, 82C are co-planar and separated by gaps 82D and 82E therebetween as shown in the FIGURES 1, 2, and 8. The plates 82A, 82B, 82C, and gaps 82D, 82B are identical to plates 86A, 86B, and 86C and gaps 86D and 86E respectively as shown in FIGURE 1. The plates 84A, 84B, 84C and gaps 84D and 84E are identical to plates 88A, 88B, 88C and gaps 88D and 88E respectively.

The gaps in the adjacent corner elements, as 82D and 84D are located so that the ends of the adjacent sealing elements, as 131 and 132 may closely engage each other,

form a tight seal, and also have a fixedly mounted support (lower end of corner plate, as 84A) for support of those adjacent ends and completion and reinforcement of the seal therebetween; the other end of each such sealing element, as 131, engages an end of the adjacent sealing element, as 130, and leans against a fixed supporting corner plate, as 82B, the thickness of which serves also to complete and reinforce a fluid tight seal between those (130, 131) elements.

The plates bearing against and supportingeach seala ing element end in its sealing position are located on the side of the sealing element toward which that end moves. The end of the corner plate at the other end of the gap (as 84D) is located to not interfere with the motion of the sealing element.

These corner plates are thin and form a thin path of contact with the inner wall of the adjacent tube in their passage therethrough. These elements are firmly joined to the frame, as shown in FIGURES 3, 4, and 7, to form a star-shaped structure. The transverse cross section of the frame is sufficiently small relative to the tubing string in which it travels and so shaped as to provide a minimum resistance to passage of fluids thereby or therepast as below described in the description of the operation.

The plates 81, 83, 85, 87, and caps 90 and 92 of frame subassembly 53 surround a frame chamber 96 with various openings therefrom to the exterior of the subassembly 53.

The upper cap 90 has a central vertical cylindrical passage 91 therethrough, and the lower cap 92 has a central vertical, cylindrical passage 93 therethrough for support and sliding movement therein of a portion of the piston subassembly 55 as below described.

The top cap 90 provides a fishing neck portion 94 at its upper portion and a plurality of transversely extending cylindrical spaces to house locking balls 107 and 108 and springs therefor.

The elements 81-88 of the frame subassembly 53 are made of thin (.15 inch thick) low carbon steel plate. Each plate as 83 and 87 is provided with slots to hold spring-urged latching elements of the seal assembly in a closed sealing position or in an open, flow position.

The piston subassembly 55 comprises an elongated piston shaft means 100 which is provided with means 104 and 105 for slidable support in frame subassembly 53, means 120 and 121 for engaging and rotating the several components of each of the sealing subassemblies, and shaft latch subassembly 106 for location of the shaft 100 in either one of two positions relative to the frame subassembly 53. Piston shaft 100 is a rigid symmetrical shaft of rectangular cross section. It fits smoothly and slidably between the heads of the shafts of the sealing subassemblies and one of its shoulders 98 (or 99) rests on one of the caps 90 (or 92) within chamber 96. It is provided with transverse slots 120 and 121 near its center and upper and lower shoulders 98 and 99 respectively and upper and lower ends 104 and 105 respectively. The upper end 104 of the shaft 100 is a solid cylinder which fits slidably, yet without rattling, in the vertical passage 91 of the upper cap 90. The upper end 104 projects upwardly of the upper cap 90 in the sealing position of the apparatus 51 as shown in FIGURES 2 and 6.

The lower end 105 of the shaft 100 is solid cylinder. It fits smoothly within the chamber 93 at the lower cap 92 in the sealed position of the sealing subassemblies 57 and 58 of the apparatus 51. The lower end 105 projects downwardly of the bottom end of the bottom cap 92 when the apparatus 51 is in the position of it parts shown in FIGURES 1 and 5.

The piston shaft locking subassembly 106 comprises a pair of locking balls 107 and 108 and springs 109 and 110 therefor. Ball 107 is located in cylinder 111 and a ball 108 is located in cylinder 112 in the cap 90. The upper end of the shaft 104 is provided with annular lockinggrooves 113 and 114. Locking groove 113 is engaged by the locking balls 107 and 108 in the position of parts shown in FIGURES 1 and 5 and locking groove 114 is engaged and held by those balls in the positions of parts as shown in FIGURES 2 and 6.

The shaft 100 is provided with four longitudinally extending slots 116, 117, 118, and 119, each slightly wider than the lug on the head of the sealing element shafts, for purposes of assembly of apparatus 51.

The shaft is also provided with a pair of transverse grooves and 121. These transverse grooves serve to control the motion of the sealing elements as below described.

The components of the sealing subassemblies 57 and 58 and their method of cooperation and structure therefor are identical to each other; accordingly the description of one sealing assembly 57 is to be applied to-the other, 58.

Each sealing subassembly such as 57 comprises a plurality of sealing elements as 130, 131, 132, 133, a seal shaft for each of said elements and a latching subassembly for each of said sealing elements.

The sealing subassembly 57 comprises four matching sealing elements 130, 131, 132, and 133; sealing subassembly 58 comprises four similar seal elements: 140, 141, 142, and 143.

Elements and are identical to each other and are both located adjacent plate 81 longitudinally spaced apart; elements 131 and 141 are identical to each other and are located adjacent to plate 85 longitudinally spaced apart. Elements 132 and 142 are identical to each other spaced longitudinally along axis of shaft 100 and are adjacent to plate 83. Elements 133 and 143 are identical to each other and to elements 131 and 141 respectively and are rotatably located adjacent to plate 87. Elements 130 and 140 are identical to each other and to elements 132 and 142 and are located adjacent to plate 81.

Elements 131 and 132 are mirror images of each other. Elements 133 and 130 are mirror images of each other. Elements 141 and 142 are mirror images of each other and elements 140 and 143 are mirror images of each other with elements 141 and 143 being identical to each other and elements 142 and 140 are identical to each other and to elements 132 and 130.

Each sealing element, as 131, operates in combination with a seal shaft therefor, as 135. The seal shaft 135 is, roughly, a T-shaped element provided with a head 136 and a shaft 137. The head 136 is located in chamber 96; the shaft rotatably fits into a circular orifice (of a seal shaft bushing) 146 in the plate 85. Similar circular bushing orifices as 146 are provided, respectively in plates 81, 83, 85, and 87 for the seal shaft of each other seal element (130, 132, 133 and 140-143).

Orifice 145 is provided in plate 81 for element 130; orifice 146 is provided for element 131; orifice 147 is provided for element 132 and orifice 148 is provided for element 133. These orifices are the same in size and shape as is the orifice 145 and bear the same relationship to the seal elements located therein as for the sealing element 131.

The shaft 137 is circular at its base to engage a circular bushing therefor, as 146. The outer portion of the shaft 137 has flat sides. These flat sides meet and match with fiat sides 148 and 149 of an orifice 160 provided therefor in the element 131.

The shoulder between the shaft and head 136 of the seal shaft 135 engages the inner side of the plate 85. A pin 138 is provided in a hole therefor in the shaft 137 and serves to hold the shaft 137 to the body of the sealing element 131 as the ends of pin 138 engage horizontally extending slots 139 and 149 in the wall of the seal element 131. This pin and slot combination permits some movement of the slotted sealing element horizontally (in position of apparatus 51 shown in FIGURE 1) relative to the length of the shaft 137 and transverse to the longitudinal axis of the apparatus 51.

The latching subassembly 150 of a sealing subassembly 131 comprises a pair of seal latches 150 and 151 and seal latch springs 151 and 153 therefor in element 131 and a pair of seal latch grooves 154 and 155 in plate '85.

The seal latch groove 154 extends longitudinally of the tool 51. The groove 155 extends (in the particular embodiment, 51) at a 45 angle to the longitudinal axis of the tool 51. The groove 154 serves to hold the seal 131, by items 150 and 151, in its open or flow position, the groove 155 serves to hold the sealing element 131 by its latches 150 and 151 in its closed or sealing position. Each sealing element as 130-133, and 140-143 has a similar longitudinally extending latching groove and a similar sealing groove to hold the sealing element in its sealing position. The center of each of these grooves passes through the center of the circular bushing orifice as 146.

This seal latch shaft receiving orifice 160 is located in the body of the sealing element 131 and is shown in FIGURE 9 as well as in FIGURE 5. Seal latch receiving orifices as 161 and 162 are also provided in the body of the sealing element 131. The springs 152 and 153 urge the seal latches as 150 and 151 into a seal latch groove such as 154 in the flow or open position of the seal latch element 131. The same relationships of seal latch elements, sea-l latch springs and grooves obtained for the other seal elements. The pin 138 limits the outward motion of the sealing element 131 relative to the plate 85 of the frame 53. The length of the slots 139 and 149 in the sealing element 131 permit each sealing element as 131 to move outward approximately A; of an inch. This play allows for motion of those sealing elements inward and outward to overcome irregularities in internal tubing diameter, the sealing elements form a sliding fit on the latch elements 150 and 151 therefor. The latch elements have a shoulder that engages the top of the adjacent bush- .ing whereby even in the expanded position of the sealing Y 6 element as 131 they form a fairly good liquid-tight seal with the face of plate as 85.

The sealing element 131 comprises an outer curved wall 176, side walls 169 and 163, an upper end wall 166, a lower end wall 167, and a bottom face or wall 165. The bottom wall or face 165 is shown in FIGURE 9. The side walls 168 and 169 are provided with slots 139 and 149 respectively therein for movement of the seal shaft pin 138 therein transversely to the length of the tool 51.

The curvature of the outside portion 170 of the sealing element 131 is such as to form a perfect mechanical fit with the inside surface of the tubing (as shown in FIG- URE 4) when the element as 131 is in its sealing position (as shown in FIGURES 7, 4, and 8).

This arrangement provides that each sealing element as 131 is resiliently urged outward, i.e. transversely to longitudinal axis of shaft 100, by the springs 152 and 153 in both the sealing element position as shown in FIGURE 2 and in its flow position as shown in FIGURE 1. The curvature of the peripheral surface of the sealing elements provides for a fir-m yet elastic seal between the sealing elements and the tubing wall in the sealing position.

The upper end wall 166 is sloped and arranged to meet with the corresponding upper end wall of the adjacent sealing element as 130 when those sealing elements are their sealing pOSitiOn. This relationship is in FIGURES 2 and 8. The lower end face 167 of the sealing element 131 is arranged to be at a 45 angle to the surface of the adjacent plates and 83 when that surface 167 is in the sealing position shown in FIGURES 2 and 8. In that position the surface 167 meets with the corresponding lower surface of the adjacent sealing element 132, as shown in FIGURE 2. Concurrently, the upper end surface 166 similarly meets with the adjacent sealing element 130 as is shown generally in FIGURE 8.

The relations of the other sealing elements with each other are the same as above described for element 131.

The head 136 of the seal shaft 135 is provided with a seal shaft lug 134. This lug is slidably located in the groove 120 of the shaft 100. Each of the seal shafts of the other seal elements 130, 132, and 133 have seal shaft lugs that each similarly engages the transverse slot 120. Similar lugs on the heads of the seal shafts for the sealing elements 140, 141, 142, 'and 143 similarly slidably engage the slot 121. Accordingly, the slots 120 and 121, and the position of the shaft determine the rotative position of the sealing shafts'and these, in turn, determine the orientation of each of the sealing elements 130-133 and 140-143. The position of the sealing of the shaft llll) is determined by pressure at the upper end 104 or lower end thereof. When the shaft 100 is moved to its lower position, as shown in FIGURE 5, the lugs as 134 are in their lowermost position and all of such lugs are held at the same level for elements -133, similarly, the lugs for the elements -143 are firmly then held in their lower position. The slots 120 and 121 are both of the same depth and are parallel to each other and perpendicular to the length of the shaft 100.

When the shaft 100 is moved from the position thereof whereat its lower end 105 is flush with the bottom of cap 92 and that shaft is moved upward from the position as shown in FIGURES 5 and 7 to the position as shown in FIGURES 2 and 6 the slots 120 and 121 are moved upwardly, the lugs such as 134 are moved upwardly, and the sealing elements are moved from their flow position as shown in FIGURES 1 and 5 to the sealing position shown in FIGURES 2 and 6.

In the flow position shown in FIGURES 1 and 5, the corner plates as 82, 84, 86, and 88 provide some longitudinal stabilization of the tool while the springs for each seal latch urge the sealing element into contact with the interior wall of the tubing, as shown in FIGURE 7, to also provide a smooth downward passage of the tool, minimizing jarring because of rattling of the tool against the sides of the tubing wall. This continued resilient contact of the apparatus 51 within a tubing avoids tilting, however the amount of resilient travel is quite small, less than of an inch average for each of the sealing elements, with the corner elements as 82, 84, 86, and 88 taking the bulk of the contact force, and the resilient element as 152 and 153 absorbing only the portion thereof corresponding to the final relations of the traveling tool and the tubing variation.

Each of the sealing elements has its forward corner, as 129 on the element 131, at an angle of about 45 to the plate adjacent as 85 whereby to override any minor bumps or scratches or accumulations of sand in the tubing.

The gaps between the portions of each corner plate such as the gaps 84D and 84B between the corner elements 84A, 84B, and 84C and similarly the gaps 82D and 82E allow the sealing elements adjacent to such gaps, as 131 and 132, adjacent to gap 84D, not only to meet with their lower surfaces, as 167 of element 131, matching the similar face adjacent thereto in the position shown in FIGURE 2 but also that the upper surface of element 131 and 132 (in position shown in FIGURE 2) join at the bottom of element 848 while the lower surface of element 131 and the lower surface of element 130 then meet and form a firm seal with the top of element 82A.

The locking balls 107 and 108 hold the shaft 100 in the position shown in FIGURES 5 or 6 until a suflicient upward vertical force is applied to the shaft end 105 (to change the shaft position from the position shown in FIG- URE 5) or to the end 104 (to move the shaft from the position shown in FIGURE 6). The grooves 112 and 113 are circular in outline and form a generally toroid-shaped cavity, with a D-shaped transverse cross section. The balls resiliently urge the shaft 100 to stay in one position (as in FIGURE 1) or the other (as in FIGURE 2). The snap action of the seal latches, as 150 and 151 of the seal 131, for each of these seals herein shown (130-133 and 140-143) further serve to hold the seals firmly in either the flow (FIGURE 5) or seal (FIGURE 6) position by latching in grooves as 154 or 155 respectively.

In operation of the process of this invention steps are made whereby the plunger apparatus 51 moves between the bottom stop 72 and the upper stop 71 in string 61. Firstly, the bottom portion 62 of the bottom length of tubing 41 of the string 61 is located above the bottom 63 of the well 60. The bottom stop 72 is then moved into the well string 61 and is located slightly above the bottom opening of 62 of the lowermost tube 43 and any choke therein.

In the producing formation 64 the top level of the oil thereof is indicated by the line 171. During oil removal from the formation there is a certain drawdown, shown exaggerated for purposes of illustration, shown by the curved portion 172 of surface 171. Surface 172 may be regarded roughly as an axially symmetrical surface of revolution with its axis of revolution lying along the center axis of the cylindrical casing 69. When the system is thus operating the top level of oil which is in the annulus 70 between the outer surface of the tubing string 61 and the inner surface of the casing 69 is shown by 174. The level 174 is shown only diagrammatically to illustrate the relations of the plunger 51 in its operation to such fluid level rather than to show the absolute value of such level to the relation of such level to the size of plunger 51. The liquid oil (and water if present) in the annulus 70 communicates by the bottom 62 of the tubing section 41 with the interior of the tubing string 61. The stop 72 is located substantial-1y below the level 174 so that the level 175 of liquid within the tubing 61, which is the same level as 174, will provide a substantial height of liquid 177 above the top cap 90 of the apparatus 51 when its cap 92 contacts stop 72. The fluids from the formation enter the interior of the casing below the level 174 through standard perforations as 67. The stop 72 is located at such depth as to always be substantially below the level 174I allowing for the fall of said level during production from formation 64.

The level of the bottom of the stop 72 is maintained, usually, above the top of the level of the perforation opening through the casing to the formation to minimize the accumulation of grit and sand in the volume of fluid directly in contact with the apparatus. After location of the stops 71 and 72 in the string 61, plunger apparatus 51 is placed in the interior of the tubing 61 with its valve subassemblies 57 and 58 in the open, or flow position, as shown in FIGURES 1 and 5.

The plunger 51 with the valve subassemblies 57, 58, in their flow position is then dropped from the top of the well as from position 180 in FIGURE 10 to the lower position 181 showing lower tip 105 of shaft in contact with the lower stop 72 but cap 92 spaced away therefrom. The gas flow from formation 64 through string 61 and outlet assembly 190 is not interrupted during this downward travel of plunger 51.

In the position 181 the sealing elements 130-133 and 140-143 are rotated to the position shown in FIGURES 1 and 5. Their outer surface is parallel to the longitudinal axis of the tool 51 and then provide a minimum transverse cross section. This cross section provides a minimum of resistance to passage of the device 51 through well fluids which are located within the tubing 21.

At the position 181 the bottom tip of the piston shaft 100 projects below the bottom cap 92 in the manner shown in FIGURES l and 5. In this position the shaft 100 of the piston subassembly 55 is in the position as shown in FIGURE 5. The springs 108 and 109 serve to hold the shaft 100 in its position, the shaft locates its slots and 121, the slots locate the lugs for the seal shafts, and the seal shaft fixes the position of the sealing elements therefor as -133 and -143. When the cap 92 of frame 53 of apparatus 51 continues to move down towards and meets the lower tubing stop, the impact of the movement of the plunger 51 against the stop 72 is applied initially to the projecting portion of the shaft 105 and overcomes the force of the springs 107 and 108, the projecting end 105 of the shaft 100 is driven into cap 92 and the shaft 100 simultaneously moves all lugs as 134 of all seal shafts as 135 from the position thereof shown in FIGURE 5 to the position shown in FIGURE 6. This movement of the seal shafts moves the seal plates elements as 131 from the position shown in FIGURES 1 and 5 to the position shown in FIGURES 2 and 6, and moves all seal elements to their sealing position across the width of the flat plates as 81, 83, 85, and 87.

The falling of the plunger 51 down the well and the contact of the plunger 51 with the tubing stop 72 at the end of that fall thus results in automatically rearranging the portion of the seal subassemblies on frame 53 to form a substantially gas tight seal across the interior of the tubing string below the top level 174 of the liquid 177 within that tubing string. The orientation of the sealing elements shown in FIGURES 2, 4, 6, and 8 blocks the free upward passage of gas and oil and water.

The plunger 51 and its sealing subassemblies 57 and 58, in sealing position as shown in FIGURES 4 and 8, smoothly fits in the interior of each of the tubing elements as 42-46 of the tubing string. The resiliency provided thereto by the springs 152 and 153 and movability by the slots 149 and 139 for each of the sealing elements also provide not only for a smooth firm seal with the tubing which seal is gas tight but also allows for variations of the diameter of such seal with the internal diameter of the tubing, such as due to the drift diameter variation of the thickness of the tubing and the size of the interior diameter at the couplings of the various tubings.

An outlet pressure regulator valve subassembly at the top of the string 61 comprises a conventional adjustable pressure regulator control valve, shown diagrammatically as 191, connected to the outlet end of outlet pipe 65, a gas-liquid separator tank, 192, a liquid outlet line 193, and a gas outlet line 196 therefrom. Line 193 operatively connects to a liquid collector tank 194. Tank 192 is provided with a conventional pressure indicator 195 to allow 9 adjustment of valve 191 as needed. Lines 193 and 196 have conventional valves and pressure controls as shown.

The gas pressure of the formation 64 is greater than the pressure provided by the pressure regulator subassembly 190. The gas pressure of the formation 64 then drives the plunger 51 up the well from the position 181 to the position 183 as shown in FIGURE 11 and then to the upper position 185 shown in FIGURE 12. During the plunger travel from its position 181 to 183 to 185 the volume 177 of the liquid oil above the plunger 51 in the position shown in FIGURE 10 is moved upward due to the pressure of the gas below the plunger 51.

The load of oil 177 thereby passes from the interior of the string of tubing 61 to the pressure regulator subassembly 190 through the orifice 68. The pressure of the gas below the plunger 51 moves the liquid 177 thereabove out through the pressure regulator valve 191 into separating tank 192 and through line 193 to an oil collector tank 194. The gas goes from separator tank 192 to a gas collector or line 196.

After the load of oil has been unloaded the continued upward motion of the plunger 51 from position 185' causes forceful contact of the upwardly projecting tip 104 of the shaft 101) against the bottom of the upper stop 71. This continued motion of the plunger 51 is due tothat the plunger is still impelled upward by the gas 199 therebelow. The striking of the projecting tip on the stop overcomes the ositioning force of the spring 107 theretofore maintaining the sealing subassemblies as 57 and 58 in sealing position and moves the piston shaft 100 down relative to the cap 90. This forceful moving of the shaft 100 downwards relative to the frame subassembly 53 results in movement of the slots 120 and 121 to the position shown in FIGURES 1 and 5 relative to the remainder of the apparatus 51. This removes the seal theretofore effected by subassemblies 57 and-58 across the interior of the tubing string v61. The weight of the plunger 51 then drives that plunger from position 185' toward the bottom of the well 60. The extremely small cross section of the plunger 51 relative to the cross section of the tubing (as shown in FIGURES 3, 4, and 7) and the small contact area of the corner plates 82, 84, 36, and 88 permits the plunger to fall down the well with the great velocity even in wells that produce up to a million cubic feet of gas per day against line pressures of 500 and 550 p.s.i.g. and permits such downward passage of plunger 51 wthout interfering with concurrent upward flow of gases from the formation 64 out of the well discharge orifice 68 and valve 190 to a gas collector line as 196.

The plates 82, 84, 86, and 88 avoid any substantial canting or locking of the plunger 51 in the tubing wall while still providing a large transverse cross sectional area in the tubing for flow of gases past the plunger when the sealing subassemblies of that plunger are in their open position. The structure of the piston 51 permits that it be extremely light in weight, although entirely adequately sturdy to perform its intended function of rapid downward passage through the well to reform a seal across the bottom thereof and, because of such light weight, to require a minimum of pressure for upward drive thereof, with a load of oil thereabove, by the formation gas. This is especially so in view of its cooperation with the plungers 71 and 72 which aid the rearranging of the components with the sealing subassemblies of the apparatus 51. On return to contact with the bottom stop 72, the plunger 51 is again located below the top level 175 of the liquid then in the tubing and the cycle of operations above described for movement of the plunger 51 and the liquid thereabove as 177 is again repeated.

The sturdy structure of the apparatus 51 provides for a great strength with the minimum of weight. This strength permits the absorption by the apparatus of the impact resulting from rapid fall through great heights repeatedly without damage to the apparatus. This lightness provides for a minimum of differential of pressure required to raise the plunger 51 and the oil as 177 carried upwardly thereabove. The stops 71 and 72 have, at their point of contact with the ends 104 and 105 of the shaft 100, a greater width and breadth than the diameter of the shaft rod 100. Accordingly, the movement of the piston rod 100 is limited to the amount by which the ends thereof, as 104 and 105, project from the top edge and bottom edge of the caps 90 and 92 respectively. Accordingly, after such limited motion of the rod 100, the remainder of the impact, due to the momentum of the apparatus 51 is absorbed by the frame subassembly 53.

In a particular embodiment of the apparatus of FIG- URE 1 for conventional tubing, with a nominal 2 inch internal diameter and an actual 1.995 inch external diameter as for F-25, H-40, J-55, and N-80 grade external upset tubing, the dimensions of the apparatus in FIGURE 1 are as in Table I.

According to another aspect of this invention which is brought out in FIGURES 10-12, prior to inserting the bottom stop 72 into the well, the temperature profile of the well 60 is first determined, and a conventional packer as 76 is placed at a level in the annular zone above the level of the producing formation 64. Frequently there are cold water zones as in the upper 500 feet of the oil well. These zones cause undesirable temperature drops and undesirable low temperature zones for the length of such water zone. A conventional pair of packers, as 77 and 78 are placed in annulus 70 below the bottom 74 and above the top 73 of such zones 75. A vacuum is created in the annulus 70 adjacent the zone 75 above the packer 77. Well fluid or other heating fluid warmer than the fluid in tubing 61 is permitted in the annular zone 70 between the outer casing 79 and the inner tubing string 61 below the level of the packer 77 in order to promote heat transfer from the earth into the tubing string below the level of the cold zone. A substantially complete vacuum is held between packers 77 and 78 between tubing string 61 and the casing 69 by the pump 179. When liquid 177 reaches the level of the packer 77, because of the vacuum in the zone between packers 77 and 78, there is a substantial decrease in what would otherwise be the normal heat loss from the small (2 to 3 inch) internal diameter string 61 and the oil 177 is transported up to the discharge zone 68 without a suflicientdrop in temperature as to initiate paraffin deposition in the zone of the well tubing at the same level as the cold zone 75.

Also, according to this invention, a choke as 178 is placed below the level lower stop 72 so that there will be a rapid separation at that level of gas from the liquid obtained from the formation 64. The temperature of the formation 64 is considerably higher than the earth surface formations and has a considerable heat capacity. The heat loss of the liquid in the volume 177 below the level 174 due to this break-out of gas effected by the choke 178 during the normal flow of liquid into the lower orifice 62 of the string 61 is not accompanied by any paraflin deposition, notwithstanding the heat loss due to evaporation due to the gases coming out of the liquid, because of the heat inflow from the formation at that level (64) resulting from the high temperature level of that formation and the fluids obtained therefrom at that level and depth. This step of initiating a break-out of gas at such a low level avoids break-out at upper levels of well 66 whereat the temperatures are lower and the flow of heat into the fluid from which that break-out would occur will be less in amount and less able to prevent paraflin deposition concomitant on temperature lowering due to evaporation. An amount of break-out sufficiently great to avoid any subsequent break-out of gas and refrigeration until the liquid is above the lowest cold zone at which break-out and paraflin deposition might otherwise occur is used at level 64 herein.

Therefore, according to this invention, in spite of the refrigerating effect of the boiling-off or evaporation of gases from liquid at and below the lower level of the oil formation liquid level 171, the heat flow from the formation to that zone below 175 maintains a temperature of the flowing fluid-gas mixture at a temperature above that at which paraffin deposition does occur. When such warmed mixture of oil and gas thereafter passes through what would otherwise be a cold zone of lower temperature, such as that zone of the string 61 opposite to and surrounded by a zone as 75, above the level of liquid 171 in the formation, the fluid-gas mixture has a very reduced tendency to effect evaporation of gas from the liquid as in the liquid volume 177 shown in FIGURE 11 and a refrigerating effect concomitant on such refrigeration and evaporation, which refrigeration, plus the cooling from the zone 75, might otherwise cause paraffin deposition. Accordingly, according to this invention, the fluid gas mixture 177 even when carried past cold zones such as 75, is not subjected to parafiin deposition, during the movement of that liquid past such zone. But for the insulating vacuum provided by pump 179 and packers 77 and 78 there could be cooling by convection as well as a refrigeration effect on liquid 177 during the passage thereof past the zone 75 or other zones elevated over 171 whereat there would be a substantially lower pressure than at the level of producing formation, 64.

The production of the vacuum and zone in the annular zone 70 is effected by an ejector or other standard type nozzle or by conventional pump means as 179 for establishing a vacuum. While there may be some minor radiation loss from the string 61 to the casing 69 in a zone such as that between packers 77 and 78, this loss is minimized as by aluminum paint on the interior casing walls between those packers.

Inasmuch as much of the heat loss usually occurring in such cold water zones is due to convection, the use of vacuum in what is otherwise known as the paraffin zone shown as 75 in FIGURE 11 is extremely effective in preventing paraffin deposition inasmuch as only a few degrees Fahrenheit change is necessary to precipitate Paraffin and, by the procedure herein disclosed, such critical although small change in temperature and thereby the undesirable deposition of paraffin on the walls of the tubing is avoided.

As below discussed, the construction of the lower tubing stop 72 herein used allows that stop to be placed at the most advantageous position for initiating the breakout rather than being limited to being placed only at the shoulders of tubing located between lengths of tubing as in conventional collar stops. This allows the location of the stop to be located with an accuracy of less than :one foot rather than :20 feet (20 feet being the usual shortest length of tubing elements). Furthermore, the very large cross sectional area provided by the stop of this invention between the interior surface of the tubing and the exterior surface of the stop allows gas which has broken out at the choke 178 therebelow to freely pass through and past the tubing stop to act on the plunger as 51 (tubing conventionally comes in 60-ft. lengths).

The lower stop 72 comprises a frame assembly 210, a slip assembly 212, and a shock-absorber assembly 214.

The frame assembly 210 comprises a frame body subassembly 216, a fishing neck subassembly 217, an upper piston chamber 218, and a lower slip retaining chamber 219.

The fishing neck subassembly comprises a fishing neck 22% and a fishing head 222 both cylindrical in transverse section and co-axial; an annular fishing neck shoulder 223 is located at the bottom of the head and is of equal width all about its circumference and joins the head with the neck. The fishing neck head has an internal bushing, sleeve 224, firmly fitted to and fixed by a screw and rivet to the head 222.

The frame body subassembly 216 has an upper cylindrical portion 226 to which the bottom of the fishing neck subassembly is firmly joined. The body and fishing neck subassembly form the exterior of the cylindrical upper piston chamber 218. Chamber 218 extends from 12 the top of the fishing neck to about halfway down the length of the body 216.

The lower portion of the frame body subassembly 216 is triangular in transverse cross section and is provided with, at its upper portion, exterior opening slots 227, 228, and 229 for the reception of the upper portion of each of slips 237, 238, and 239, respectively. The lower portion of the body 216 is hollow and cylindrical and provides a chamber, the lower, slip-retaining chamber, 219, for reception of the lower portion of the slips 237, 238, and 239. Base 250 forms the ceiling of chamber 217.

The slip assembly 212 comprises the slip retainer ring 232, a slip retainer spacing bolt 234, and the slips 237, 238, and 239. Slips 237, 238 and 239 are identical to each other. Each slip as 237 comprises an exteriorly corrugated and interiorly upwardly and outwardly sloped upper portion 241 and a lower arm portion 242. The outer side of the lower end 243 of portion 242 is provided with slot 244 to engage the ring 232. The corrugated portion 241 has biting teeth of coldworked steel arranged in a corrugated surface as 247, 248, and 249 for each of the slips 237, 238, and 239 respectively. The inner surface 251 of the corrugated portion 241 is smooth and engages the outer surface of the slot, 227, therefor. The inner portion of the ring 232 is threaded and the bolt 234 engages those threads. Adjustment of the bolt 234 provides for raising and lowering of the maximum spacing of the retainer ring 232 relative to the base 250 of body 216 in order to control the maximum lateral travel of the slips 237, 238, and 239 along the sloped surfaces of the slots 227, 228, and 229 provided therefor.

The retaining ring 232 engages the slots as 244 at the lower portion of each of the arms of each of the slips.

The shock absorber subassembly 214 comprises a piston 254 and a spring 256.

The piston comprises a flat cylindrical head 257, an upper cylindrical shaft 258, an O-ring groove subassembly and a lower cylindrical shaft 268. The O-ring subassembly comprises shoulders 261, 262, and 263 with grooves 259 and 260 separated by the shoulder 262. The shaft 258 slidably fits in the bushing 224. A spring 256 sits on the base 266 of the piston spring chamber 218 and extends to the bottom of the lower shoulder 263 of the piston 254. The chamber 218 is provided with an orifice 278 which orifice is cylindrical, smooth-surfaced and extends perpendicularly through the wall of the chamber 218. Spring 256 has an internal diameter that is larger than and does not contact the lower shaft 268. O-rings 269 and 270 are located in the grooves 259 and 260. The bushing 224 contacts and holds the upper shoulder 261 against the action of the spring 256.

In operation the stop 72 is held by a fishing tool and lowered into the well for desired depth. During the lowering of the apparatus the components thereof are in the relationship shown in FIG. 13, namely the corrugated portion of the slips are at the lower position at the bottom of the outer slots 237, 238, 239 provided therefor in the outer wall of the body subassembly 216 with the shoulders, as 287, of each slip as 237 resting on the bottom of the slots therefor.

On reaching a desired level of location a downward jar is applied to the body of the tool 72 by a jarring tool as shown in my co-pending patent application Serial No. 107,837, filed May 4, 1961. The movement results in movement of the slips 237, 238, and 239 from their position as shown in FIG. 13 to that of FIG. 14. The upward motion of the slips due to the outwardly sloped surface of the slot 227, 228, 229 result in an outward movement of the toothed surfaces 247, 248, 249 of those slips to contact the interior surface of the wall of the adjacent tubing as section 41 as shown in the position of the slips in FIGS. 14 and 16. The bolt 234 prevents additional motion upward and undesirable force of lock- 13 ing by spacing the retainer ring 232 at a predetermined distance from the bottom or base of the base 250 of the body 216.

Accordingly the apparatus 72 is readily located at any vertical level desired. The apparatus is removed from its position by a jarring up action, as by my tool deposition as shown in FIGS. 13 and 14.

Stop 72 provides impact resisting forces that rapidly, but not instantaneously, reach a maximum, although predetermined, value after the first contact between the moving plunger 51 and the s'hock'receiving piston face 255. This insures a movement of the shaft 100 of the piston subassembly 55 of the apparatus 51 from position shown in FIGURE 1 to its URE 2. 1

In the position of the stop 72 shown in FIGURES 10 and 11 the orifice 278 and top of chamber 218 are both substantially below the level 175 of liquid 177 in the tubing string 61. Accordingly the chamber 218 is always position shown in FIG- 'full of liquid, primarily oil, as 271, during the operative condition of this apparatus. Liquid is shown only in FIGURE 14 for clarity of representation of parts in FI URES 13, 15, and 16.

The head 257 of the shock absorber subassembly has a {fiat upper surface 255. It is this surface which is met by the lower end of the piston shaft 100 at the end of the downward .travel -of the plunger apparatus 51 as shown in FIGURE 10 and, as above described, immediately thereafter by the cap 92 which is pushed downward by the momentum of the tool 51. This rapid downward .motion of the tool 51 forces the shock absorber subassem- ,bly (more slowly) downward not only against the force of the spring 256 but, more importantly, against the vol- ,ume of liquid captured within the cylindrical chamber 218. The only escape for this liquid is through the small orifice 278. The rapid flow of a substantial amount of fiuid through that small orifice provides a substantial although; gradually applied resistance to the downward travel of the piston subassembly 254 and, accordingly, causes the shaft end 105 to be pushed with a snap action ,--into the lower end cap 92- of the apparatus 51. This movement of the apparatus 51 at stop 72 reliably causes F the piston-shaft 100 to move upward from the position ,shown in FIGURES 1 and to the position relative to its frame subassembly 53 shown in FIGURES 2 and 6. This 1 movement by the stop 72 provides to shaft 100 a gradual application of a substantial impact resultant from momentum rather than an instantaneous shock as might be developed were stop head 257 fixedly attached to the tubing.

'The fluid 271 acts asthe initial shock absorbing member 1 rather than the spring 256.

An extended spring as 256 in FIGURE 14 would have only its minimum force available to oppose the downward rush of the tool 51. Stop 72 provides for a rapidly developed large predeterminable applied force resisting the momentum of the downwardly moving tool 51 to insure that the rearrangement of the sealing subassemblies 57 and 58 relative to the frame subassembly 53 will be accomplished at the end of the downward motion of the apparatus 51 through the tubing string 61. 2

After the reaction of liquid 271 absorbs the initial impact of tool 51, the spring 256 gradually increases its force of resistance to the downwardly moving tool 51; the force required to move the piston subassembly shaft =268 is far greater than the force required to compress spring 256 in the first one-half inch of downward travel of shaft 268 following the initial contact of face 255 and head 257 whereby the lower, shocking stop, 72, provides a decreasing rate of change of resistance to the movement of the plunger thereagainst with increasing downward movement of the top shaft portion of that stop.

The downwardly moving tool 51 forces head 257 downwards, as shown in FIGURE 15. The O-rings and the fluid 271 bear the initial impact of the momentum of tool 51; the spring 256 takes on the load after the initial shock absorption by the liquid. The orifice 278 is located above the bottom of chamber 218 and below the lowermost position of the O-rings of the piston shaft 253 in its compressed position as in FIGURE 15. The spring 256 returns the piston subassembly 254 from its compressed position to the position of FIGURE 14 after load is taken from surface 255.

According to this invention the shocking stop 72 transmits the vertical impact provided by the first contact of the lower tip, 105, of shaft and, thereafter, of the cap 92 to the slips as 237, 238, and 239; the slips in turn are urged laterally by slots 227, 228, and 229 and transmit a transverse as well as vertical thrust to the tubing. The tubing is cylindrical and metallic and resilient, and the slips contact only three widely spaced apart portions thereof. Thereby the distensibility of the tubing is used to absorb part of the shock resulting from the dropping of a four-lb. steel mass, as 51, for 2,000 to 5,000 feet. This shock absorbing aspect of this structure is obtained by using spaced apart slips and supports therefor; the spacing apart of the slips as 237, 238, and 239 provides channels as 265, 266 and 267 between the sides 275, 276, and 277 of the body of the stop for flow of gas and liquid therethrough with a minimum of interference.

While an extended spring provides for a minimum energy absorption or transfer at the time of initial contact of a moving object, stop 72, to the contrary, provides a reliable substantial shock or impact of predetermined value when piston shaft 268 is fully extended because, at this time, the liquid in chamber 218 is at its maximum inertia and maximum weight. The first contact of the projecting tip of the moving plunger 51 with the top of the stop 72 is met by a maximum resistance, the force to get the liquid 271 moving through the orifice 27S, rather than a minimum force which would result if only a fully extended spring were operating to oppose the motion of plunger 51.

While the lower stop is directed to obtaining a sharp positive thrust on the lower end 105 of shaft 100 in spite of the relatively slow downward rate of travel of piston 51 against a substantial upward flow of gas (which fiow continues upward while the piston falls downward) the upper stop 71 is directed to softening the force of impact of the usually very rapidly upwardly traveling piston 51 there being entirely enough impact to rearrange sealing subassemblies as 57 and 53 at that upper stop.

The upper stop 71 comprises a fixed frame subassembly 290 and a movable piston assembly 291. The frame subassembly 290 comprises a cylindrical piston cylinder wall 292, a top cylinder head 294 with an orifice 295, a laterally extending annular collar 296, a lower cylinder opening 297, and an intermediate cylinder wall orifice 298. The collar 296 extends between ends of lengths of neighboring tubing, as 46 and 47, of the string 61. The outer surface of the cylinder 292 fits freely into the 2 inch internal diameter of the tubing element 46 of the string 61, with an annular space 293 therebetween.

The piston subassembly comprises a shaft 299 and a spring 300. Shaft 299 has attached thereto conventional O-rings 302 and 304 nested between shoulders 301, 303, 305. The shaft 299 has a narrow upper portion 306 and a lower wider portion 307; The lower portion has a flat bottom face 308. The O-rings form a free sliding fit with the walls 292. The shaft 299 is movable upwardly to the position shown in FIGURE 18.

A lower shoulder 309 projects inwards from wall 292 and limits the lower extension of shaft 299. The internal orifice of shoulder 369 slidably engages piston shaft portion 307 and has a lesser internal diameter than the outer diameter of shoulder 305.

The wall 292 and head 294 and O-rings define a piston chamber 310. The lower end of the subassembly 291 has a fiat lower surface 368. It is this surface which is met by the upper end 1S4 of the piston shaft 100 at the end of the upward travel of the plunger apparatus 51 as shown in FIGURE 12 and, as above described, immediately thereafter by the cap 90 which is pushed upward by the momentum of the tool 51. This rapid upward motion of the tool 51 forces the piston shaft 299 upward against the force of the spring 369 and, less importantly, against the volume of gas within the cylindrical chamber 310. The free escape for this gas is provided by orifices 298 and 295. The rapid fiow of a small amount of gas through those two orifices provides a negligible amount of resistance to the upward travel of the piston subassembly 291.

As shown in FIGURE 18, the tool 51 forces head 308 upwards. The extended spring 300 takes the initial shock. The spring 300 gradually increases its force of resistance to the upwardly moving tool 51. Thereby the upper shocking stop provides an increasing resistance to the movement of the plunger thereagainst with increasing upward movement of the piston shaft portion of said stop. This causes a very gradual adsorption of shock of the impact of the rapidly upward moving tool 51 and minimizes shock to the piston 55 and seal control shafts of apparatus 51. There is, however, adequate impact of head 104 on face 308 to cause the shaft end 104 to be pushed into the cap 9% of the apparatus 51. The movement of the apparatu 51 at stop 71 thereby softly yet reliably causes the piston shaft ltlt) to move downward the predetermined amount of height of end 104 above cap 90 from the position shown in FIGURES 2 and 6 to the position relative to its frame subassembly 53 shown in FIGURES 1 and 5 where end 104 and cap 90 are fiush. This movement of shaft 100 by the stop 71 provides for a gradual application of a snubbing force to the sealing subassemblies 57 and 58 relative to the frame subassembly 53 and to frame 53 at the end of the upward motion of the aparatus 51 through the tubing string 61 rather than an instantaneous shock as might be developed were stop head 308 fixedly or firmly attached to the tubing 46.

The orifice 298 is located below the top of chamber 310 and above the highest position of the O-rings 303 and 304. The spring 300 returns the piston subassembly 291 to the position of FIGURE 17 after compressive load is taken away from surface 368. Orifice 68 is located below the highest position of the bottom face 368.

Dimensions of stop 71 are given in Table II.

Dimensions of stop 72 are given in Table III.

TABLE I.DIMENSIONS OF APPARATUS 51 Item Dimension Measurement (in.)

Length, cap 90-92 11% Thickness 85 87.. 1 Thickness em ....do 0.133 Outer edge S2-outer edge 86 12s Channel 93 of Cap 92 Diameter Length... 1% Groove 144 Depth 020 Angle t0 shaft 100.. 1 45 57-58 spacing Length.... 3% Shaft 1G0..." .(lo. 12 Groove 114... Diametc 3132 D cpth- O25 Seal 131 Length. 2% Width... -70 IIeight.... A6 Slot 139 Lengthm. tz Thickness. %2 51 Material Steel 1 Degrees.

TABLE II.DI1\IENSIONS OF LOWER STOP 72 Item Dimension Measurement (in.)

Frame 21 O.d 1% Chamber 219.. l Chamber 218 3 it Orifice 278 fs: Head 257. 1 Slot 2'57 h: l 4 gth 3% Shaft 258 Length 1 ,2 .d ii Shaft 2158-..- r 1% "its Piston 254.. 4% Slit) 2l2 "/62 Arm 2 12 2'35: lie Surface 247 Length.... 3 Thickness.... 76 Cd. radius 7?; 72 Materi ll Steel Steel 1 Degrees.

TABLE III.DIMENSIONS OF UPPER s'ror 71 Item Dimension Measurement (111.)

Wal. 292 l. 850 1. 50 8 Piston 307 (portion) 1. iii) 3F Portion 301i Head 291 2% Hole 29a l[ole 293 at: Head 29141010 4 Although in accordance with the provision of the patent statutes, particular preferred embodiments of this invention have been described and the principles of the invention have been described in the best mode in which it is now contemplated applying such principles, it will be understood that the operations and constructions shown and described are merely illustrative and that my invention is not limited thereto and, accordingly, alterations and modifications which readily suggest themselves to persons skilled in the art without departing from the true spirit of the disclosure hereinabove are intended to be included in the scope of the annexed claims.

I claim:

1. An apparatus for unloading an oil and gas producing formation comprising (a) a Well extending from said formation to the ground surface therea'bove, said well comprising a string of oil Well tubing within a casing, openings from said casing to said formation and from the interior of said easing into the bottom of said string of tubing, and an outlet from said tubing to above said surface,

(b) an upper shocking stop in said tubing string near to the top of said string of tubing, a lower shocking stop in the tubing string near the bottom of said tubing string, the internal diameter of said tubing string being substantially the same between said stops,

(c) a reciprocating piston within said tubing, said piston comprising a body elongated in the direction of the length of said string, a series of sealing elements encircling said body; each of said sealing elements being movably mounted on and extending laterally of said body, and sealing element support means pivotally supporting each of said sealing means on said body, means attached to and holding each said sealing element in either of two positions, a sealing position extending across said body length or an open position parallel thereto, each said sealing element having two ends and an outer curved surface between said ends, one end of each of said sealing elements in said series engaging an end of an adjacent sealing element in said series, the outer surface of each of said sealing elements in sealing position engaging and matching substantially all of a series of adjacent portions of said interior surface of said tubing surrounding said piston neighboring to said series during upward passage of said piston in said tubing between said lower and upper stops, said sealing elements each then extending from said piston body to said outer surface of said sealing element and the outer curved surface of each of said sealing elements then forming a fluid-tight seal with said interior surface of said tubing, and said series of sealing elements forming with said body a fluid-tight seal across the interior of said tubing, said sealing elements being movable at said upper stop, to a position whereat the ends of adjacent sealing elements are spaced apart from each other.

2. Apparatus as in claim 1 comprising control means movable within said body and attached to and holding each said sealing element support means in either of two positions and comprising also resilient means between said body and each said sealing element and urging said sealing element outwardly toward said tubing, and means on said sealing element support means limiting the outward movement of the sealing element supported thereby.

3. Apparatus as in claim 1 also comprising, in said piston, a sealing element control means comprising a control shaft longitudinally movable from one position to another in said body and seal element control means connected to each of said sealing elements and to said shaft rotatably mounted in said body, latching grooves in said body extending from the center of rotation of said seal element control means, and latching element therefor into contact with one of said grooves and urging said outer surface of said sealing element into contact with inner surface of said tubing, and resilient means supported in said body contacting and holding said control shaft in one or the other of two positions.

4. Apparatus as in claim 1 wherein said lower shocking stop comprises body, gripping means attached to spaced apart portions of said tubing and supporting said body, and shock absorber means supported by said body, said shock absorbing means comprising a cylindrical chamber in said body, said chamber comprising a bottom, side walls and a top shoulder, a piston movable along the length of said chamber, liquid sealing means between said piston and said chamber spaced away from the bottom of said chamber, an orifice extending from the interior of said chamber to the exterior of said body and located between said sealing means and said chamber bottom when said piston is in its compressed condition and compressed spring means between said piston and the bottom of said cylindrical chamber and urging said piston to maintain an extended position.

5. Apparatus as in claim 1 wherein said tube gripping means comprises a plurality of like spaced apart slips each comprising radially outer serrated portions and an inner smooth surface sloped upwardly and outwardly and said body has a plurality of matching upwardly and outwardly sloped surface for movement of each of said slips upwardly and outwardly therealong and downwardly and inwardly therealong.

6. Apparatus as in claim 1 comprising also a formation of lower temperature than other formations through which said casing passes, annular sealing means between said tubing and said casing above and below said low temperature formation, an annular space bounded by said annular sealing means, said lower sealing means located above the level of oil in said formation, and pumping means with 18 an inlet and an outlet, the inlet operatively connected to said space between said tubing and said casing, said pumping means adapted to maintain a vacuum in said annular space bounded by said sealing means.

7. Apparatus as in claim 6 comprising also choke means in said tubing below the level of the lower shocking stop.

8. Apparatus as in claim 6 comprising also pressure regulating means at the outlet of said tubing.

9. A piston for unloading an oil and gas producing formation comprising a body, a series of sealing elements encircling said body; each of said sealing elements movably mounted on and extending laterally of said body, and sealing element support means pivotally supporting each of said sealing means on said body, means attached to and holding each said sealing element in either of two positions, a sealing position extending across said body length or an open position parallel thereto, each said sealing element having two ends and an outer curved surface between said ends, one end of each of said sealing elements in said series engaging an end of an adjacent sealing element in said series, the outer surface of each of said sealing elements in sealing position engaging and matching substantially all of a series of adjacent portions of an exterior cylindrical surface surrounding said piston and neighboring to said series said sealing elements being movable to a position whereat the ends of adjacent sealing elements are spaced apart from each other.

10. Apparatus as in claim 9 also comprising a sealing element control means comprising a control shaft longi tudinally movable from one position to another in said body and seal element control means connected to each of said sealing elements and to said shaft and rotatably mounted in said body, latching grooves in said body extending from the center of rotation of said seal element control means, and latching element therefor into contact with one of said grooves and urging said outer surface of said sealing element outwardly and resilient means supported in said body contacting and holding said control shaft in one or the other of two positions.

11. A shocking stop comprising a body, tube gripping means supporting said body, and shock absorber means supported by said body, said shock absorbing means comprising a cylindrical chamber in said body, said chamber comprising a bottom, side walls and a top shoulder, a piston movable along the length of said chamber, liquid sealing means between said piston and said chamber spaced away from the bottom of said chamber, an orifice extending from the interior of said chamber to the exterior of said body and located between said sealing means and said chamber bottom when said piston is in its compressed condition and compressed spring means between said piston and the bottom of said cylindrical chamber and urging said piston to maintain an extended position.

12. Apparatus as in claim 11 wherein said tubing gripping means comprises a plurality of like spaced apart slips each comprising radially outer serrated portions and an inner smooth surface sloped upwardly and outwardly and said body has a plurality of matching upwardly and outwardly sloped surface for movement of each of said slips upwardly and outwardly therealong and downwardly and inwardly therealong.

ROBERT M. WALKER, Primary Examiner. 

1. AN APPARATUS FOR UNLOADING AN OIL AND GAS PRODUCING FORMATION COMPRISING (A) A WELL EXTENDING FROM SAID FORMATION TO THE GROUND SURFACE THEREABOVE, SAID WELL COMPRISING A STRING OF OIL WELL TUBING WITHIN A CASING, OPENINGS FROM SAID CASING TO SAID FORMATION AND FROM THE INTERIOR OF SAID CASING INTO THE BOTTOM OF SAID STRING OF TUBING, AND AN OUTLET FROM SAID TUBING TO ABOVE SAID SURFACE, (B) AN UPPER SHOCKING STOP IN SAID TUBING STRING NEAR TO THE TOP OF SAID STRING OF TUBING, A LOWER SHOCKING STOP IN THE TUBING STRING NEAR THE BOTTOM OF SAID TUBING STRING, THE INTERNAL DIAMETER OF SAID TUBING STRING BEING SUBSTANTIALLY THE SAME BETWEEN SAID STOPS, (C) A RECIPROCATING PISTON WITHIN SAID TUBING, SAID PISTON COMPRISING A BODY ELONGATED IN THE DIRECTION OF THE LENGTH OF SAID STRING, A SERIES OF SEALING ELEMENTS ENCIRCLING SAID BODY; EACH OF SAID SEALING ELEMENTS BEING MOVABLY MOUNTED ON AND EXTENDING LATERALLY OF SAID BODY, AND SEALING ELEMENT SUPPORT MEANS PIVOTALLY SUPPORTING EACH OF SAID SEALING MEANS ON SAID BODY, MEANS ATTACHED TO AND HOLDING EACH SAID SEALING ELEMENT IN EIGHER OF TWO POSITIONS, A SEALING POSITION EXTENDING ACROSS SAID BODY LENGTH OR AN OPEN POSITION PARALLEL THERETO, EACH SAID SEALING ELEMENT HAVING TWO ENDS AND AN OUTER CURVED SURFACE BETWEEN SAID ENDS, ONE END OF EACH OF SAID SEALING ELEMENTS IN SAID SERIES ENGAGING AN END OF AN ADJACENT SEALING ELEMENT IN SAID SERIES, THE OUTER SURFACE OF EACH OF SAID SEALING ELEMENTS IN SEALING POSITION ENGAGING AND MATCHING SUBSTANTIALLY ALL OF A SERIES OF ADJACENT PORTIONS OF SAID INTERIOR SURFACE OF SAID TUBING SURROUNDING SAID PISTON NEIGHBORING TO SAID SERIES DURING UPWARD PASSAGE OF SAID PISTON IN SAID TUBING BETWEEN SAID LOWER AND UPPER STOPS, SAID SEALING ELEMENTS EACH THEN EXTENDING FROM SAID PISTON BODY TO SAID OUTER SURFACE OF SAID SEALING ELEMENT AND THE OUTER CURVED SURFACE OF EACH OF SAID SEALING ELEMENTS THEN FORMING A FLUID-TIGHT SEAL WITH SAID INTERIOR SURFACE OF SAID TUBING, AND SAID SERIES OF SEALING ELEMENTS FORMING WITH SAID BODY A FLUID-TIGHT SEAL ACROSS THE INTERIOR OF SAID TUBING, SAID SEALING ELEMENTS BEING MOVABLE AT SAID UPPER STOP, TO A POSITION WHEREAT THE ENDS OF ADJACENT SEALING ELEMENTS ARE SPACED APART FROM EACH OTHER. 